It presses most of the buttons Apple's rumored Music Locker service does, except the online storage and computing infrastructure is already in place.

Which is where Cloud Drive becomes an odd bait-and-switch.

Amazon's press release and promotion has focused exclusively on the music aspect – with some mention that the actual space is in Amazon's bulletproof S3 storage service – Amazon Cloud Drive is not exclusively a service to store music.

The free 5GB of basic storage is the same as you'd get signing up for the Amazon Web Services (AWS) Free Usage Tier, though that would also give you 10GB of Elastic Block Storage, 750 hours of Linux VM usage, load balancing, Internet data transfer, 25 hours of use and 1GB of storage on an Amazon SimpleDB database, 100,000 HTTP requests and 10 Cloudwatch alarms.

Cloud Drive is a lot cheaper than S3, which costs $0.14 per month per gigabyte for the first terabyte. That's $1.68/GB/year compared to $1/GB/year for Cloud Drive.

Cloud Drive also only supports MP3 and AAC file formats. So if you're a little more heterogeneous and don't like the bother of having to convert your files, or an audiophile who prefers other formats, you're out of luck.

Downloading from Cloud Drive and uploading to your device should work, but you wouldn't be able to stream music wirelessly to a device on which you don't store music.

Being able to stream your music is a step up in functionality from JBOD storage in a cloud. That's an improvement in consumer services, though not a huge one.

Conceptually it's another step toward self-service cloud-based hosting of all kinds of things – which may eventually include your OS, data, identity metadata and all kinds of other things, so you'll never be caught out when you need to produce proof of insurance, car registration, tax data, personal history, employment status, bank accounts, credit score and all kinds of other things that would be perfectly safe storing in the cloud and streaming wirelessly in the open to your unsecured handheld device.

You might want to remind your friends who are enthusiastic about technology but just a touch naive about some of those other issues before they start using Cloud Drive for things that are more important than music, though. Just because S3 is secure doesn't mean using always is.